How to send 'data' to ASMX web service via AJAX POST?

Question

I can successfully receive values from my web service so in that repect the script is working fine. However I am now trying to send data to the webservice using the 'data' field below. What i cant figure out is how to send a simple string (e.g. "test") to the web service which is what my web method expects as a parameter.

Any help is much appreciated. For example:

function setQuestion() {
$.ajax({
    type: "POST",
    **data: "{}",** //how do i use this to send a string??
    dataType: "json",
    url: "http://someURL",
    contentType: "application/json; charset=utf-8",
    success: onSuccess
});
}

function onSuccess(msg) {
$("#questiontxt").append(msg);
}

Solution 1

For asmx you need to pass a stringified version of the data object, so for example:

var data = "{param1:" + param1IsANumber +
           ", param2:\"" + param2IsAString + "\"}";
$.ajax({
 data: data,
 dataType: "json",
 url: url,
 type: "POST",
 contentType: "application/json; charset=utf-8",
 success: function (result) {}
});

Or you can hava an object and use jquery-json

var data = {};
data.param1 = 1;
data.param2 = "some string";
$.ajax({
 data: jQuery.toJSON(data),
 dataType: "json",
 url: url,
 type: "POST",
 contentType: "application/json; charset=utf-8",
 success: function (result) {}
});

Finally, your web service class must look like:

[WebService(Namespace = "http://www.somedomainname.com/")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
[ScriptService]
public class MyService : System.Web.Services.WebService
{
  [WebMethod]
  [ScriptMethod(ResponseFormat = ResponseFormat.Json)]
  public void MyServiceCall(int param1, string param2)
  {
  }
}

Solution 2

jQuery takes the data argument and converts it into the appropriate type of request variables.

So you use something like:

data: { myParameterName: "myParameterValue", myParameterName2: "myParameterValue2" }

and jQuery does the rest of the work for you.

A specific example based on a comment:

data: { toSend: "test" }

Comments

[Mr-DC]

Thanks for that Dave, however I still get an exception: "Invalid JSON Primitive: value"...

[Mr-DC]

Hi petrov, I get the "Invalid JSON Primitive" exception for your solution too. Also do i need a method in the web service called 'GetData' to retrieve that data?

[Dave]

Can you post the declaration for the ASMX function you're trying to post to?

[Mr-DC]

Its ok dave, this way worked: data: '{"value": "test"}',

[Dave]

That's odd, you shouldn't need to send the data as a string. But I guess if it's working....

[petrov.alex]

ok, my solution is not working because I used the same quotes

[Mr-DC]

Yea, actually i do have another question now, what if i wanted to send the value of a variable like this: var toSend = "test"; data: '{"value": toSend}', Note this doesnt work, i just tried :(

[Dave]

Updated my answer to reflect your specific parameter name and value.

[cdm9002]

Dave, you must send as a string for asmx. Davey1990, use $.toJSON()..see my answer below.

[cdm9002]

Great. You are actually supposed to quote the param names, e.g. "{\"param1\":" + p1 + "}" but it does actually work without :)